Apparatus for electrolyzing fused salts of metals and recovering the metals and acid radicles



6, 1924' 5 Sheets-Sheet l E. A. AsHcRoF' Filed Feb THE METALS AND ACID RADIGLES Ill/lll Jan. 12 1926.

APPARATUS FOR ELEcTRoLYZ-ING FUSED sALTs oF METALS AND RECOVERING Jan. 12 1926. 1,569,606

APPARATUS FOR ELECTROLYZING FUSED sALTs 0F METALS AND REcovERING E. A. ASHCROFT THE METALS AND ACID RADICLES Filed Feb. 6, 19424 5 Sheets-Sheet 2 6, 1924 5 Sheets-Sheet 5 Jan. 12 1926.

E. A. ASHCROFT APPARATUS FOR ELECTEOLYZING FUsED sALTs oF METALS AND RECOVERING THE METALS AND ACID RADIGLES Filed Feb.

/N VEN To@ EDGAR' H HSHCRoF-r B/C/rwn. m

Jan.v 12 1926.

S E L w T D 4 FA% oRl R D cme H A S D@ AMF d S AMM E MF M E H T APPARATUS FOR ELECTROLYZING FUSED SALTS OF METALS AND RECOVERING 5 Sheets-Sheet 5 C N H R 0 S nh/m i NH l H i Patented Jam/12, 1926.

UNITED STATES PATENT oFFlcE.

EDGAR ARTHUR ASHCROFT, OF LONDON, ENGLAND.

.APPLIR'A'JTU'Sl FOR ELECTROLYZING FUSED SALTS 0F METALS AND BEGOVEBING THE METALS AND Application led February To all whom z't may concern.:

Bc it known that I, EDGAR ARTHUR ASH- Cuorr, a subject of the King of Great Britain, residing at 32a Liverpool Street, in the city of London, England, and at l-Vaye, near' which is the subject matter of application for Letters Patent Serial No. l551,306 and bearing date the 10th 4day of April A. D. 1922.

l have found that the multiple-couple electrolyzers which I have invented and vclaimed under my said application are adapted for, and can, by suitable modification, be employed with advantage in, recovering, from fused salts, metal lighter than the fused electrolyte, such, for instance as magnesium from fused magnesium chloride, by processes in accordance withl Letters Patent No. 1,359,- 653 granted to me and dated the 26th day of November A. D. 1920.

I will, for the purpose of description, presume that my present invention is to be used for the obtainment of metallic magnesium from chloride of magnesium in accordance with my aforesaid Patent 1,359,653 from which its analogous applications will also be understood.

In adapting the said'multiple-couple electrolyzers for such purpose I employ a suitable modiication of the electrodes thereof` either in one elect-rolyzer, or in a pair of electrolyzers, whichor both of which, can be used alternately as a primaryand as a secondary electrolyzer, or I canemploy two electrolyzers, one being used as a primary electrolyzer for the production of the alloy of magnesium and some suitable heavy metal (such for example as lead) and magnesium and the other being used as a secondary electrolyzel` for the production of the metallic magnesium, the alloy being passed from one -electrolyzer to the other by any suitable means for causing the said alloy to pass successively, or circulate, through "the electrolyzers. In this latter case the electrodes of the secondary electrolyzer' may be of iron,

ACID RADICLES.

6, 1924. Serial No. 690,969.

or steel, whilst those of the primary electrolyzer may be of carbon, or graphite.

The containing vessel, or chamber', of the electrolyzer, o r of each electrolyzer, is preferably of considerable depth relatively to its length' and width, or cross-sectional area, and the electrodes are constructed so as to contain alloy, they being, for instance, inthe form of trays, (I will refer to them as trays) and are horizontally arranged, each tray being capable of holding a considerable amount of -molten lead alloy (lead-magnesium alloy in the instance given the under side-of the trays being preferab y made of a shape, which will facilitate the escape of the magnesium deposited on the electrodes, suitable openings, or passages being ,provided for the upward passage of the liberated magnesium and gases, the upper part of the electrolyzer being-provided with anoutlet for chlorine, an inlet for magnesium chloride and openings for enabling the'produced magnesium' to be collected.

When two electrolyzers are employed theyare preferably arranged in one and the same electric circuit and can beoperated by passing the electric current through the two electrolyzers lalternately in opposite directions so that at first portions ,of the alloy carried at the'upper sides` of the electrodes will be the negative oles in one electrolyzer and the positive po es in the other electrolyzer, and vice vers, when the current is reversed and therefore in the irst electro.-

surface of each electrode and will rise through the openings therethrough, and pass ``lyzer chlorine will beliberated at the under off to any required place whilst magnesium will be liberated at the upper surface of the alloy and enrich it, the electrolyte consumed being replacedv to maintain a `proper level during the electrolysis. At the same time,

inthe secondary electrolyzer, chlorine is generated at the surface of the alloy carried by the electrodes and combines with the magnesium of the alloy, whilst metallic magnesium will be liberated from the magnesium chloride at the under surface of the .electrodes and rise to the surfaceA in the electro lyzer and can be' removed by any suitable means. V

When the electrolysis has proceeded in this manner for the requisite time the elec- Atric current is'reversed and the electrolyzers lwhich were primary and secondary become respectively secondary and primary electrolyzers. This reversal of the current may be repeated at any desired intervals by any suitable means, such as a reversing swtcn Worked mechanically', or electrically, or by hand. The reversal of the current will make no alteration in the difference of potential in the combined electrolyzers as the rise of terminal voltage in one electrolyzer will compensate for the fall of terminal voltage 1n the other electrolyzer.

When the electrolyzers are employed each exclusively as either a rimary, or V as a secondary, electrolyzer, t e alloy will be circulated from one electrolyzer to the other by allowing the alloy to descend in succession from one toanother of the electrodes in the primary electrolyzer and thence td flow, or be raised, from the lower part of the electrolyzer and subsequently to pass through the secondary electrolyzer, there being in this case, no reversal of the electric current the circulating alloy becoming enriched in the l rimary electrolyzer and impoverished in t e secondary electrolyzer.

I do not confine myseln to the particular details hereinbefore described as the may be varied without departing from t e nature of my invention. I may also employ my electrolyzers as aforesaid, separately, either as rimary electrolyzers for the production oi) magnesium-lead alloy, or as secondary electrolyzers for the production of magnesium from such alloys. I may employ anyr other suitable heavy metal instead of lead and, instead of magnesium chloride, I may similarly electrolyze any other suitable salt of` magnesium, or of other light metal, or admixtures fof Such salts with other salts.

Constructions and arrangements of `the said multiple-couple electrolyzers in accordance with this invention are illustratedin the accompanying drawings, but I do not limit myself to the particular details illustrated. Figures 1 and 1a together'constitute a vertical section of a pair of electrolyzers in accordance with this invention -shewing, diagrammatically, electric connections arranged so that by reversal of the current the electrolyzers can be used alternately as primary and secondary electrolyzers.

Figures 2 and 2a together constitute a vertical section of a pair of similar electrolyzers through which the alloy is circulated by any suitable means which are indicated diagrammatically, the electric current passing in series through the two electrolyzers.

Figures 3 and 4 shew, in plan and transverse section respectively, and drawn to a i larger scale, one of the tray electrodes.

AIn the electrolyzers illustrated the containing vessel of one of the pair is marked `lent amount and this ma A and the containing4 vessel of the other of the pair is marked A2. The electrodes are marked B and B2 respectively. The upper sides of theA said electrodes constitute trays, or equivalent containers, for the alloy the lower sides of each tray, or equivalent container, being formed with convexities b, above the recesses, or pockets, b2, .in the upper side of the electrode next under it, but the undersides may be of any other suitable shape but preferably are such as will facilitate, as much as possible, the upward passage of alternatelyk the chlorine andthe magnesium equally throughout the fused magnesium chloride. The electrodes are in- .sulated from each other which can be done and, when the electric circuit is passed in the direction indicated by the. full line arrows, the electrolyzer A2 is the primary electrolyzer, magnesium chloride being fed into the hopper a2 and chlorine passing through the passages o* in the electrodes B2 and out of the electrolyzer at D2.- -When this action has continued for the requisite time for the alloy in the pockets b2 of the electrolyzer A2 to havey become enriched in magnesium to a sufficient extent, (say to an extent of four per cent, for instance) and the electrolyte having passed into the electrolyzer A through any suitable connecting passage, or communication, the alloy in the pockets b2 of the electrolyzer A will have become depleted of magnesium to an equivanesium, being lighter than the electrolyte rises therein and vpasses up through the passages b* in the electrodes B and can be removed from the surface of the electrolyte in any suitable wayg' for instance, electrolyte and collecting the magnesium at the overflow D. The electrolyzer A, there- V fore acts as a'secondary electrolyzer whilst by passing in further I cated by the dotted arrows, and the electro-4 A lyzer A then acts as the primary electrolyzer and the electrolyzer A2 acts as the secondary electrolyzer.

The electrical connections and conductors are shewn diagrammatically only. They may be arranged in any suitable way so that, by manipulating the reversing switch E, the electric current will pass alternately through the metal casings and central conductors of the electrolyzers alternately in the direction indicated byvthe full line arrows and in the direction indicated by the dotted arrows, the

' molten magnesium chloride being yin communication with lower and upper inlets and outlets in any convenient man-l ner.

One of the electric conductors is connected to the top electrode of 'the ile,- or of each pile, by a conductive rod the' other electric conductor being in electrical con'- nection with the lowest electrodes offthe pile, or of each pile, in any suitable way and the electrolyzer is encased, or enclosed, in electrical, and heat, insulating material which can be done in a manneranalogous to the manner in which it is done in the case of the multiple-couple electrolyzer of the parent patent application Serial No.' 551,306 filed April 10, 1922. This will be evident from the accompanying drawings and requires no particular description here. Figure 2 illustrates an arrangement wherein two electrolyzers, like those shewn in Figure 1, are arranged so that the elec-l trolyzing current passes therethrough constantly in the same direction, one electrolyzer being used for enriching the alloy and the other electrolyzer being used for depleting the alloy -which will be circulated in cascade down through the electrodes B, B2,

in the respective electrolyzers and through suitable passages taking the course indicated by the dotted lines and arrows, the assed into the electrolyzer A, at a, and enriching with magnesium the alloy therein, chlorine escaping at D at top and the alloy being pumped (pumps are indicated at C) 'up to, and passing through the inlet a2 down through the electrolyzer A2, wherein the magnesium, set free by electrolysis inthe said electrolyzer, passes up to the top and can be removed, or be caused to pass 0E, by the action of the pumps, 'the alloy being con tinuously returned to the electrolyzer A, to be again enriched with magnesium from fresh charges of fused magnesium chloride and so on.

There are passages for the alloy, in stag'- gered series, ,through the electrodesl B and B2. These passages are shewn as being constituted by small pipesl b passed through holes in the electrodes and extending up to the level of the surface of the alloyin the pockets b2 and down to, or into, the alloy in the pocket below. The pockets in each electrode communicate with each other by passages b2 also. ata level witlifthe surface of the alloy so that the alloy, in its course 1 through the electrolyzers, maintains the pockets b2 charged with alloy to the requisite level, the arrangement of the lpassages for the circulating alloy being such that'it does not interfere with the ascending clilorin'e in` the primary electrolyzer, or with the ascending magnesium in the other electrolyzer. What I claim is v v 1. Themethod ofeife'cting electrolysis of a light metal which comprises alloying the samewith a heavy metal, decomposing the fused alloy simultaneously. at electrolytic couples in electrical series below the surv face ofthe fused electrolyte, and removing' the'li ht metal'at the top of the melt.`

l2. T e method of effecting electrolysis of a light, metal whichconiprises alloying the 'saine with a heav metal, decomposing ,the

fused alloy simu taneously at electrolytic couples in electrical series below'the surface of the fused electrolyte, causing the disengaged lightmetal `to rise through the several electrolytic. couples to the top of gthe melt and there removing it.

3. The method of effecting electrolysis ofy a light metal which comprises alloyingv the same with a heavy metal, decomposing the fused alloy simultaneously at electrolytic couples in electrical series belowl the surface of the fused electrolyte,'and discharging the light metal continuously` as it rises to the top of the melt.

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4. The method of effecting electrolysis of a light metal which com rises alloying the saine with a hea 'met decomposin the fused alloy simtaneously at electro ytic cou les in electrical seriesbelow the sur ace of t e fused electrolyte,and discharging the light metal continuously by overiiowas it rises to the topof the melt.

5. The method of recoverin a light metal which com risesalloying t e same with heavy meta yby multiple-couple electrolysis, f

and then decomposing the-alloy by multiplecouple electrolysis to separate` the light metal from the heavy metal.

6. The method of recovering alight metal which com rises alloying the same with a heavy meta by multiple-coupleelectrolysis, ltransferring the alloy to an independent electrolytic vesseland there decom osing the alloy by multiple-couple electro ysis and se arating the light metal.

E. An electrolytic method which comprises ,passin electric current-in series throu h a plurality of multiple-cou le electro ytic cells, causin heavy and'lig t metals to become alloy inone cell, leading the alloy to a second cell and there decomposing the alloy for'recovery of the llight metal. i

' 8. Apparatus for effecting electrolysis, comprising a plurality of multiple-couple electrolytic cells, means for effecting a heavy l metal light metal alloy in one cell, means for leading said alloy to a second cell, and means for effecting multiple-couple electrolysis of the alloy in the second cellcto decompose the alloy for the, recovery of the light metal.

9. An elect-rode. for use in a multiplecouple' electrolyzer, said electrode having adished upper surfaceto form a container for electrolyte.

10. An electrode for use in a multiplecouple clectrolyzer, said electrode having a idished upper surface to form a container for electrolyte, and being recessed to .afford .riserpassage means to permit the upward flow of fluid therethrough.

11. An electrode for use in a multiplecouple electrolyzer, said electrode having a dished Vupper surface to form a container for electrolyte, :and being recessed in the marginal area of the depression inthe upper face ofi-the electrode to aord riser passage fluid therethroug electrode being shaped to guide fluid to said riser passage means. 13. An electrode for use in a multiplecouple electrolyzer, said, electrode. comprising a plate-like member provided on its upper surface with a plurality of cup-like depressions to contain the electrolyte.

14. An electrode for use in a multiplecouple electrolyzer, said electrode comprising a plate-like member provided on its upper surface with a plurality of cup-like depressions to contain the electrolyte, and

being pierced -in the marginal areas of the v several cups to afford riser passages for the upward flow of electrolytic,v products.

15. An electrode for use in a multiplecouple electrolyzer, said electrode comprising a plate-like member provided on its upper surface with a plurality of cup-like depressions to contain the electrolyte, and being pierced in the marginal areas of `the several cups to afford riser passages for the upward flow of electrolytic products, the' lower face of the electrode being shaped to guide upward flowing electrolytic products to said passages.

In testimony whereof I have signed my name to this specification.

EDGAR ARTHUR jAsnonor'r. 

